1. Field of the Invention
This invention relates to a layer structure of surface coating applied, for instance, to vehicle bodies, which provides a feeling of transparency and depth, to a method for applying same and to a novel laminate and novel vehicle body.
2. Description of Related Art
Surface coatings applied to vehicle bodies are intended essentially to protect a vehicle body surface against scratches and improve the durability of it. In recent years, in addition to this purpose, such a surface coating is also intended to meet a call for a high quality of external appearance of a coated vehicle body which provides an impulse to users' sensitivity. In order to improve coating quality, it is indispensable to intensify a feeling of the depth of coating and a feeling of the transparency of coating, and to use pure coating colors of low lightness and high chroma.
Another strong tendency or requirement is directed to coal-black surface coating which can offer a feeling of luxury appearance and a feeling of depth. However, conventional surface coatings are rendered difficult to offer these feelings, which are attributable to scattering of light caused by various elements, such as an outer surface of the surface coating, pigments and/or dyes contained in the coating layers, and the layers themselves. This is because, scattering of light makes it difficult to decline sufficiently the lightness of color which is one of the barometers or indices of black.
Conventionally, in order to improve feelings of coating quality and luxury appearance of a surface coating, of which a color clear layer, as a white/black shielding layer, has a thickness greater than approximately 100 .mu.m, is coated over a color base layer, there have been proposed various surface coating structures. One surface coating structure uses such a coloring material or agent of the color clear layer that it has a hue within +/-10 divisions from the contrast point in the 100-division Mansell hue ring to a hue of a coloring material or agent, such as a pigment, of the color base layer. Such a surface coating structure is known from, for instance, Japanese Unexamined Patent Publication No.3-157167. Another surface coating structure has a color base layer containing a coloring material or agent such as a pigment, whose color is relatively dark or deep, and a color clear layer containing a coloring material or agent such as a pigment of a high chroma of color similar to or the same as the color of the color base coloring agent or material, as described in Japanese Unexamined Patent Publication No.61-238366. Further, Japanese Unexamined Utility Model Publication No.1-108726 reveals a surface coating structure with a transparent clear layer which contains a dye as a coloring material and is applied over a color clear layer coated on a color base layer by what is called a "wet-on-wet coating". Otherwise, in order to enhance a feeling of depth of a surface coating, a brilliant material, such as powdered aluminum, may be contained in the color clear layer as described in Japanese Unexamined Patent Publication No.62-79874. Further, a plurality of different color of color clear layers may be applied one after another as described in Japanese Unexamined Patent Publication No. 58-202080.
Another approach to high quality of surface coatings is to improve coating techniques which can provide a precise control of thickness and uniformity in thickness of coating layers.
In conventional ways of surface coatings described in, for instance, Japanese Unexamined Patent Publication Nos.59-4471 and 2-68169, while a subject surface is horizontally moving, a pair of spray devices or guns disposed above and laterally aside the course of movement of the subject surface, which are reciprocally movable approximately in directions perpendicular to the moving direction of the subject surface, spray paints onto the subject surface. Such a surface coating manner is essential to move the spray guns so as to overlap partly their painting patterns. Consequently, a surface coating can not be made uniform in thickness between overlapped part and non-overlapped part. In addition, because of the zig-zag tracks of painting at small pitches by the spray guns, it is difficult to form a uniform thickness of surface coating.
Particularly, as to a surface coating having a color clear layer which contains a coloring dye whose transparency is generally high as compared with those of pigments and allows vivid or clear color to come out well on the clear layer, the surface coating is greatly influenced on coloring by its thickness. Consequently, unevenness in the thickness of a surface coating induces lacking in color uniformity of the surface coating. Further, because after light transmits a color clear layer to a color base layer, it is reflected by the color base layer and transmits the color clear layer, with an increase in lightness of the color base layer, lack in color uniformity of the surface coating becomes a significant problem. Accordingly, a larqe unevenness in thickness of the surface coating, such as 10 .mu.m of unevenness in thickness, allows only colors, almost near black, to be available to surface coatings.